Currently, the IPv6 (Internet Protocol version 6) is regarded as a core standard of the next generation Internet. In the next generation Internet, it is confirmed that the IPv6 has to support multicast, and possess a large number of multicast address space. After the IPv6 is put into application, more and more pure IPv6 nodes appear. However, due to a huge scale of an existing IPv4 (Internet Protocol version 4) Internet network, the IPv6 protocol network is not going to replace the existing IPv4 network overnight. Many IPv4 nodes still persist because of their successful operation. Therefore, the evolution of the network is certainly smooth and progressive, and the IPv6 network and the IPv4 network inevitable coexist for a long time in future Internet. During the long coexistence, according to an IPv6 deployment strategy, pure IPv6 networks keep emerging regionally. In this case, the pure IPv4 network and the pure IPv6 network coexist and interlace with each other in the network.
Therefore, a mechanism is required to ensure direct communication between a pure IPv4 node and a pure IPv6 node to realize a smooth transition. At present, quite a number of transitional technologies for unicast interworking have been proposed; however, they are only applicable to unicast communication, but not applicable to multicast communication. At present, no authoritative interworking transitional scheme is provided in the aspect of multicast. However, multicast applications such as IPTV (Internet Protocol Television, Internet protocol television) video are widely deployed. Therefore, when the IPv4 and the IPv6 coexist, how to achieve the interworking between these multicast applications is a key problem that needs to be solved, and multicast interworking ability needs to be effectively provided.
At present, an IPv4-IPv6 multicast protocol conversion technology exists in the prior art, where the technology may use an ordinary IPv6 multicast protocol to communicate with any multicast group supporting the IPv4 protocol without changing an infrastructure. Its core idea is: one or multiple IPv4-IPv6 multicast conversion apparatuses are placed on a path between a source using one IP protocol and a destination using another IP protocol. The IPv4-IPv6 multicast conversion apparatus performs conversion between IPv4 and IPv6 multicast, and performs conversion between an IPv4 multicast packet and an IPv6 multicast packet. A one-to-one mapping relationship between IPv4 and IPv6 multicast addresses needs to be established to represent one same multicast activity in two networks. A header of a multicast packet is converted according to the mapping relationship and support of a relevant application protocol, for example, an ALG (application layer gateway, Application Layer Gateway) protocol, is needed, so as to accomplish multicast interworking.
However, this IPv4-IPv6 multicast protocol has a low conversion performance, and cannot support large-scale multicast applications.